Exercise-induced oxygen desaturation determinants including pulmonary emphysema in COPD: ECLIPSE data

Abstract

Background: Exercise-induced oxygen desaturation (EID) is common in patients with Chronic Obstructive Pulmonary Disease (COPD). We investigated: (1) the prevalence of EID; (2) the relative-weight of several physiological determinants of EID including pulmonary emphysema, and (3) the relationship of EID with certain patients9 clinical characteristics. Methods: 2050 COPD subjects (age: 63.3 ±7.1years; FEV 1 : 48.7 ±15.7%pred.) were recruited. EID (SpO 2 ≤88%) in the six-minute walk test (6MWT), emphysema quantified by computed-tomography (QCT), and clinical characteristics were analysed. Results: 435 subjects (21%) exhibited EID. Subjects with EID had more QCT-emphysema, lower walking distance (6MWD) and worse health-status (BODE, ADO index) compared to non-EID. EID was progressively increased across emphysema-degrees in GOLD II (≤9fold) but this increase was lower in GOLD III-IV. Determinant of EID were obesity (BMI≥30kg/m 2 ), FEV 1 (≤44%pred), moderate or worse emphysema, and low baseline-SpO 2 (≤93%). Each point increase on the ADO-score independently elevated odds ratio (≤1.5fold) for EID. Conclusions: About one in five COPD subjects in the ECLIPSE cohort presents EID. Emphysema severity is more related to EID in GOLD II compared to GOLD III-IV. Moreover, obesity, airflow obstruction, and low baseline oxygen saturation increase the odds for EID. Emphysematous patients with high ADO-score should be monitored for EID.